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Evolutionary Transformation (evolutionary + transformation)
Selected AbstractsEvolutionary transformation of the hominin shoulderEVOLUTIONARY ANTHROPOLOGY, Issue 5 2007Susan G. Larson Despite the fact that the shoulder is one of the most extensively studied regions in comparative primate and human anatomy, two recent fossil hominin discoveries have revealed quite unexpected morphology. The first is a humerus of the diminutive fossil hominin from the island of Flores, Homo floresiensis (LB1/50), which displays a very low degree of humeral torsion1, 2 (Fig. 1; see Box 1). Modern humans have a high degree of torsion and, since this is commonly viewed as a derived feature shared with hominoids,3,6 one would expect all fossil hominins to display high humeral torsion. The second is the recently discovered Australopithecus afarensis juvenile scapula DIK-1-1 from Dikika, Ethiopia, which seems to most closely resemble those of gorillas.7 This specimen is the first nearly complete scapula known for an early hominin and, given the close phylogenetic relationship between humans and chimpanzees suggested by molecular studies,8,13 one would have expected more similarity to chimpanzees among extant hominoids. [source] Patterns of evolutionary transformation in the petrosal bone and some basicranial features in marsupial mammals, with special reference to didelphidsJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 1 2002M. R. SÁNCHEZ-VILLAGRA Twelve petrosal and four nonpetrosal characters were coded for representatives of all 15 extant genera of Didelphidae and for 16 additional genera of marsupials representing all extant orders. Three basal metatherians were used as outgroup comparison. Histological sections of a subset of the data were examined. An intermediate position of the hiatus Fallopii supports the monophyly of Didelphidae. Several basicranial regions support different clades within the Didelphidae that recent molecular work has identified, including a sister group relationship of Caluromys and Caluromysiops, the monophyly of large opossums, a Lestodelphys-Thylamys clade, and a Lestodelphys-Thylamys-Gracilinanus-Marmosops clade. Glironia lacks petrosal and jaw synapomorphies of Caluromys and Caluromysiops. The transverse canal, a synapomorphy of the crown-group Marsupialia, opens as a single foramen anterior to the carotid foramen in most marsupials or as numerous foramina in the pterygoid fossa in diprotodontians. It is either intramural (most marsupials) or simply endocranial (most diprotodontians excluding koalas and wombats). Loss of a deep sulcus in the anterior pole of the promontorium for the internal carotid artery and a rostral tympanic process of the petrosal also characterize the groundplan of the crown group Marsupialia. Pouch-young wombats show a groove in the anterior pole of the petrosal for the internal carotid artery. The absence of a prootic canal foramen in the tympanic side of the petrosal of adults supports the monophyly of Australidelphia. Some pouch-young marsupials possess a prootic canal that is later lost in ontogeny. A rather flat promontorium and a crest running medio-distally in the middle of the promontorium characterize Macropodidae. Zur Evolution des Petrosum und des Basicranium bei Beuteltiere, unter besonderer Berücksichtigung der Didelphiden Zwolf Merkmale des Petrosum und vier Merkmale des Basicranium wurden bei Vertretern aller Gattungen der Didelphidae sowie bei 16 zusätzlichen Taxa der Marsupialia untersucht. Drei basale Metatheria wurden als Außengruppen verwendet. Histologische Schnittserien von verschiedenen Arten wurden in die Untersuchung einbezogen. Einige monophyletische Gruppen innerhalb der Didelphidae, die durch molekulare Analysen identifiziert wurden, werden durch im Rahmen dieser Arbeit gewonnenen morphologischen Merkmale unterstützt, u. a., das Schwestergruppenverhältnis von Caluromys und Caluromysiops, die Monophylie von großen Opossums, sowie die Monophylie der Taxon-Gruppe Lestodelphys-Thylamys-Gracilinanus-Marmosops sowie der Gruppierung Marmosa-Micoureus-Monodelphis. Glironia fehlt die Synapomorphien von Caluromys und Caluromysiops, die in dieser Arbeit gefunden wurden. Das Fehlen des `deep sulcus' für die Arteria Carotis communis am Vorderende des Petrosum, ein Processus rostralis anterior des Petrosum und der Canalis transvs. werden als Synapomorphie der Kronengruppe Marsupialia gewertet. Das Fehlen des Canalis prooticus bei Cranien von Adultstadien unterstützt das Monophylum Australidelphia. Einige Beuteljunge von Australidelphien besitzen einen Canalis prooticus, der später in der Ontogenese zurückgebildet wird. Die Öffnung des Canalis transvs. liegt bei den meisten Marsupialia rostral zum Foramen caroticum, während bei den Diprotodontia die Öffnung aus verschiedenen Foramina in der Fossa pterygoidea besteht. Der Canalis transvs. ist entweder `intramural' oder einfach endocranial (Diprotodontia, aussschließlich Koalas und Wombats). Beuteljunge Wombat besitzen am Vorderende des Petrosums eine Rinne für die Arteria carotis interna. [source] The "Transformation" of Governance: New Directions in Policy and PoliticsAUSTRALIAN JOURNAL OF POLITICS AND HISTORY, Issue 1 2004John Loughlin The terms transformation and governance are used increasingly in the academic literature but often in a confused way. This article attempts to define both terms. It argues that there are three kinds of transformation: pseudo-change; incremental evolutionary transformation (IET), which is the most common form; and revolutionary transformation (RT). It applies this model of change to three paradigm shifts in developed countries since 1945: the Welfare State; the neo-liberal state; and the so-called Third Way. It argues that each of these paradigms involves a particular dominant mode of governance: statist; pluralist; and network respectively. It examines both the causes and consequences of these transformations for politics and policy. [source] The evolution of the protonephridial terminal organ across Rotifera with particular emphasis on Dicranophorus forcipatus, Encentrum mucronatum and Erignatha clastopis (Rotifera: Dicranophoridae)ACTA ZOOLOGICA, Issue 2 2010Ole Riemann Abstract Riemann, O. and Ahlrichs, W.H. 2009. The evolution of the protonephridial terminal organ across Rotifera with particular emphasis on Dicranophorus forcipatus, Encentrum mucronatum and Erignatha clastopis (Rotifera: Dicranophoridae). ,Acta Zoologica (Stockholm) 91: 199,211 We report on the ultrastructure of the protonephridial terminal organ in three species of dicranophorid rotifers (Dicranophorus forcipatus, Encentrum mucronatum and Erignatha clastopis). Differences between the three species relate to shape and size, the morphology of the filter region and the number of microvilli and cilia inside the terminal organ. A comparison across Rotifera indicates that the terminal organs in D. forcipatus display a number of plesiomorphic characters, but are modified in E. mucronatum and Er. clastopis. This is in accordance with the results of phylogenetic analyses suggesting a basal position of D. forcipatus compared with the more derived species E. mucronatum and Er. clastopis. Moreover, we survey available data on the terminal organ in Rotifera and discuss its evolutionary transformations. The protonephridial terminal organ in the common ancestor of Rotifera consisted of a cytoplasmic cylinder with cilia united into a vibratile flame and a single circle of circumciliary microvilli. Depending on the topology on which characters are optimized, the site of ultrafiltration was formed by longitudinal cytoplasmic columns spanned by a fine filter diaphragm or by pores in the wall of the terminal organ. In several taxa of Rotifera, the terminal organ , probably independently , lost its circumciliary microvilli. [source] | ||||||||||